A frequently cited problem with the use of integrated combined-cycle coal gasification plants is that, if the plant must be operated in the mid-range mode, some of the expensive gasification and gas cleaning equipment must remain idle during such an operational mode. This is a distinct economic disadvantage.
Thus it would be desirable to be able to fully utilize all of the gasification/gas cleaning equipment whether or not the power plant is operated base loaded. It is well recognized that it would be of advantage to be able to use this equipment upon demand for the generation of intermediate BTU gas or for the synthesis of storable liquid fuels, such as methanol. However, as now contemplated, the former would require the incorporation in the system of an oxygen plant and the latter requires the capability for compressing the intermediate BTU gas to 2000 psi together with a relatively complex reactor and product separation system.
It would be advantageous to be able to incorporate in a coal gasification power plant the capability for generating intermediate BTU gas during mid-range mode operation without the imposition of significant additional capital charges.